The related art leveling devices have the deficiency of poor drag and drop performance. Simply put, the related art is susceptible to damage caused by the moment created by applying a force to the foot of the leveler by moving the support structure (i.e. furniture). Support within a furniture leg via a propel nut, for example, counteracts torque applied to the foot of a leveling device. Longer propel nuts may be used to provide better support as the foot is coupled to the propel nut with a threaded stud. However, longer propel nuts are difficult and expensive to form as they are stamped from sheet steel and drawn longer and longer by a progressive die. This is difficult however due to thinning of the material and long propel nuts are difficult to tap.
FIG. 1 is a partial cross-sectional view 100 of a prior art leveler 109 attached to a wood, plywood, or pressboard substrate 101. Alternatively, levelers may be used with plastic substrates. The substrate 101 may be a furniture leg or support. The device may be, for instance, applied to industrial equipment. A propel nut 104 resides in a bore 102 of the substrate 101. The propel nut has skives 105 which engage the bore 102 of the substrate and surrounding substrate material and which assist in retaining the propel nut in the substrates. The propel nut has a flange 107 which abuts exterior surface 106 of the substrate 101. The propel nut is fixed in the substrate. The flange surface 108 engages the surface 106 of the substrate. A threaded stud 103A is threaded into the propel nut 104 and is rotatably and translationally movable with respect to the propel nut.
The threaded stud 103A includes an integral nut 109A and floor engaging surface 109B. Threads 103 extend from the nut 109A to the end of the stud. The threaded stud 103A rotates and moves translationally with respect to the internal threads of the propel nut. In this way the floor engaging surface 109B may be positioned relative to the substrate (i.e. leg of the furniture) to adjust the height of the furniture with respect to the floor. When the propel nut is installed into the substrate there is a slight rotational movement of the skives 105 and the barrel of the nut as the nut is forced into the bore 102 of the substrate 101. The height of the leveler is based on the translational movement of the threaded stud within the propel nut. Deformation 130 occurs in the substrate 101 near the surface of the propel nut as it is forced into the substrate.
FIG. 2 is a bottom view 200 of the prior art leveler in substrate 101. The wood substrate has cracks 201 in the surface 106 and distortions 210 or bowing in the plane of the wood. The cracks or other disruptions in the surface are caused by dropping or sliding the furniture. Dropping applies a force generally along the axis of the threaded stud 103A and dragging applies a force generally perpendicular to the axis of the threaded stud 103A.
Propel nuts are used in the furniture industry to secure levelers in substrates. Propel nuts are shorter than the threaded studs which are inserted inside the propel nut so that adjustments may be made. The height of the prior art leveler is changed by adjusting the threaded stud relative to the propel nut.
When extended to its full length, the leveler is especially susceptible to bending or breaking which can damage either the substrate or the entire piece of furniture. The leveler is more susceptible when fully extended because the bending moment or torque which is applied when the furniture is moved by sliding it on the floor is large. Also, the furniture may be lifted and dropped which tends to fracture the substrate 101.
Correcting a defect in an article supported and positioned by a leveler can be difficult, time consuming, labor intensive, and expensive. In some cases, the entire substrate or the furniture may have to be discarded and/or the furniture disassembled if a leg of the furniture is fractured.
Two approaches to solve the aforementioned problems involve the use of thicker side panels or longer propel nuts. Use of aforementioned thicker side panels adds to the weight of the substrate and can significantly add to the expense of the furniture produced. Longer propel nuts also contribute to increased cost in manufacturing the final piece of furniture.
Levelers for the legs or walls of furniture are also sometimes described as leveling mounts, swivel levelers, rigid levelers, adjustable feet, leveling pads, furniture glides, leg levelers, desk glides, table glides, furniture sliders, threaded T-nuts for wood legs, and low profile levelers. U.S. Pat. No. 4,991,365 to Jackson discloses a foot pad attached to a shaft portion for leveling panels in a relocatable wall. U.S. Pat. No. 6,129,431 to Hansen Jr. et al discloses the use of a built-in riser in the base of a wall section. U.S. Pat. No. 4,770,275 discloses the use of a riser in an adjustable ladder assembly. U.S. Pat. No. 5,138,814 to Giles et al. discloses the use of a nut-and-bolt type leveler consisting of a threaded bolt portion which cooperates with a nut against a washer to extend or retract a foot.
The structure of the instant invention and the advantages its provides will be readily apparent to a person of ordinary skill in the art when reference is made to the Summary of the Invention, Brief Description of the Drawings, Description of the Invention and Claims which follow hereinbelow.